Conventionally, as a method for the measurement of a two-terminal circuit is known a Kelvin connection measurement method (four-terminal resistance measurement method) is known. In the measurement method by Kelvin connection, each terminal of the two-terminal circuit is connected with probes respectively constituting parts of an electric current supply circuit and a voltage measurement circuit, thereby making it possible to inspect the two-terminal circuit without being affected by any circuit resistance of the electric current supply circuit and the voltage measurement circuit, as well as any contact resistance between the probes and the terminals.
As one of Kelvin inspection fixtures to be operated through the measurement method by Kelvin connection to inspect semiconductor integrated circuits and semiconductor devices (hereinafter simply referred to as “IC and others”), there have been proposed such as, for example, those disclosed in Patent Document 1. The Kelvin inspection fixture thus disclosed has two contact probes which are arranged in parallel with each other. Each of the contact probes includes an electrode side top end portion contactable with one of solder ball electrodes each forming part of the IC, and a land side top end portion contactable with one of lands respectively formed on a circuit substrate to be connected with an inspection circuit. Each of the electrode side top end portions has two inclined surfaces inclined in different angles with respect to the axial direction of the contact probe, and ridge lines formed with the two inclined surfaces and arranged to face each other.
The conventional Kelvin inspection fixture as disclosed in the above is configured to have the ridge lines of the electrode side top end portions wedged into the solder ball electrode while being securely engaged with the solder ball electrode, thereby causing oxides on the surface of the solder ball electrode to be broken, and thereby ensuring that the contact robe can electrically be connected with the solder ball electrode.